1. Field of the Invention
This invention relates to platforms or carriers incorporating at least one magnetic transducer for reading from and writing on a data carrier. It is applicable in particular to magnetic read/write transducers for magnetic peripherals of data processing systems, in particular disc memories.
2. Description of the Prior Art
In present day data processing systems, increasingly frequent use is being made of magnetic disc memories, by reason of their storage capacity and the relatively short time which is taken by the magnetic read/write transducers to access data contained anywhere on the discs from the time when the transducers receive an order to access this data from the said processing system.
It is known that magnetic discs carry data in concentric circular recording tracks whose radial width does not exceed a few hundredths of a millimeter and which generally cover the major portion of both faces of the discs.
In operation, the discs are rotatably driven at constant speed by an electric motor. To enable data to be written on and read from a disc, magnetic transducers are arranged above each face of the disc at a distance of a few .mu.m. Current practice is usually to associate a single platform or carrier provided with one or more transducers with each face of a disc. A platform fitted with a plurality of transducers becomes necessary when it is desired to achieve a substantial reduction in the time taken by any transducer to access any item of data contained on the face of the disc.
The transducers are generally magnetic transducers containing a magnetic circuit which has an air gap and a winding arranged around it. The air gap enables data to be read from and written onto the discs. Generally, but not exclusively, transducer carriers or platforms having one or more transducers are in the form of a relatively rectangular parallelpiped, whose major face adjacent the disc, termed the lower face, contains the air gaps of the transducers. The opposite major face, termed the upper face, containing the electrical points and wires which enable the windings of the transducers to be connected to the electrical circuits of the disc memory with which they are associated.
When the transducers of an associated platform are not performing the operations of reading or writing data from or onto the associated face of the disc, the platform occupies, in relation to the disc, a so-called "rest" position in relation to the disc which is different from that which it occupies during reading or writing.
Among the various kinds of platforms of this nature, the platforms to which the invention relates are those usually known as "unstick from contact" or "fly off" transducer carriers or platforms. These types of platforms are being more readily accepted and more widely used in the industry. Such carriers have a lower major face, termed the flight surface, which rests on the associated face of the disc when the carriers are in the rest position (the disc being stationary). The flight surface has a first part termed the main flight surface which is in the form of skids which rest on the disc when the latter is stationary, and a second part in the form of a bevel which is inclined in relation to the skids and which is situated at the "front" of the platform. Conventional usage defines the "front" of the flight surface as that part of the surface which, when the face of the magnetic disc associated with the platform is travelling past the flight surface, is the first in time to have pass before it the data on this face of the disc. Similarly, the part of this surface which is the last in time to have pass before it the same data is termed the rear of the flight surface. These definitions will be used throughout the instant specification and claims. The air gaps of the transducers are situated at the rear of the flight surface and carried by the skids.
When it is desired to cause the transducer platform to move from its rest position to its flying position above the face of the associated magnetic disc, it is merely necessary to set the disc in rotation. After a fairly short period, the platform rises by virtue of the lifting effect created by the bevel and rotation of the disc. When the disc reaches its nominal speed of rotation, the platform is in the flying position. The surface of the skids are inclined relative to the face of the disc and this imparts to the carrier enough lift for it to fly stably above the disc. The platform is thus enabled to fly by the lift from the skids.
When the disc is turning, dust or any other similar unwanted contaminant material infiltrates between the disc and the flight surface of the platform. Because the air gaps are situated at the rear of the skids, which in flight form an angle with the disc, this dust becomes concentrated in the region of the air gaps. There is thus a danger of the dust clogging the air gaps and thereby adversely affecting the signal read from or written onto the disc by the transducers as well as the quality of the facing surfaces of the platform and the associated disc.
It can, therefore, be seen how advantageous it would be to have a means of forcing the dust away from the air gaps, and if possible, away from the skids so that no dust whatever is picked up by the carrier.
It is precisely to this problem that the present invention provides a solution.